Wireless communication system, wireless communication device and wireless communication method, and computer program

ABSTRACT

An information transmission source forms a transmission packet at a predetermined time unit into which a preamble is inserted and transmits it. The information reception target returns an acknowledge (ACK) packet or a not acknowledge (NACK) packet into which a preamble is inserted. A hidden terminal recognizes that the transmission path is used for data retransmission from when the NACK is received to when the next ACK is received to avoid collisions. Further, when there is transmission data at the information transmission source specified by a beacon signal, it is recognized that the transmission path is used until the next ACK is received. For example, in an ultra wide band communication method, access control is executed while avoiding collisions of communication communications and a retransmission control is executed.

TECHNICAL FIELD

This invention relates to a wireless communication system, a wirelesscommunication apparatus, a wireless communication method, and a computerprogram, for mutual communication among a plurality of wirelessstations, and particularly to a wireless communication system, awireless communication apparatus, a wireless communication method, and acomputer program, for effecting access control with avoiding collisionsof communication and a retransmission control.

More specifically, the present invention relates to a wirelesscommunication system, a wireless communication apparatus, a wirelesscommunication method, and a computer program, for access control withavoiding collisions of communication and a retransmission control in theultra-wide band communication system and particularly to a wirelesscommunication system, a wireless communication apparatus, a wirelesscommunication method, and a computer program, for providing an accesscontrol with avoiding collisions of communication and a retransmissioncontrol with that communication apparatuses being currentlynon-communicating hold the use condition of transmission path throughwhich data communication or retransmission is executed between othercommunication terminals.

BACKGROUND ART

Construction of an LAN (Local Area Network) by connecting a plurality ofcomputers provides sharing information such as files and data, sharingperipheral devices such as a printer, and interchanging information suchas forwarding electronic mail or data content.

Conventionally, the wired LAN connection with optical fibers, coaxialcables, or twist-pair cables was general. This case requires wiringconstructions, which makes it difficult to simply construct a networkand makes works for laying cables troublesome. Further, after theconstruction of a LAN, the length of the cable connected to a devicelimits the movable range.

Then, wireless LANs draw attention as a system releasing users from theLAN wiring in the wired system. According to the wireless LAN, atoperation spaces of offices or the like, most of all part of wiringcables can be omitted, so that communication terminals such as personalcomputer (PC) can be moved relatively easily. Recently, the demands haveremarkably increased with the advance in high speed in the wireless LANsystem and lowering the cost. In particular, to construct a small scaleof wireless network among a plurality of electronic devices existingaround human beings to effect information communication, recentlyintroducing a personal area network (PAN) has been studied. For example,different wireless communication systems are defined using frequencybands for which governmental licenses are not required such as the 2.4GHz band, the 5 GHz, and the like.

In a communication system constructed of a plurality of terminals, it isknown that an access control is necessary to avoid collisions ofcommunication between terminals. The access control in the wirelessnetwork includes the channel occupied system such as the FDMA (FrequencyDivision Multiple Access: Frequency Division Multiple Access), the TDMA(Time Division Multiple Access: Time Division Multiple), the CDMA (CodeDivision Multiple Access: Code Division Multiple Access), or the channelshared system such as the ALOHA or the CSMA (Carrier Sense MultipleAccess: Carrier Sense Multiple Access).

For the packet communication having a high burst characteristic due torandom communication demands, the channel shared systems, in which aplurality of terminals share the same frequency channel, are frequentlyadopted. In this channel shared system, communication requests randomlydone from the terminals may cause collisions of signals from a pluralityof terminal stations (i.e., transmission at the same time interval).Since the collision will decrease the service quality in communication,as a method for avoiding this, the CSMA/CA (Carrier Sense MultipleAccess/Collision Avoidance: Carrier Sense Multiple Access/CollisionAvoidance) system is widely adopted.

Further, it is known that “Ad Hoc communication” freely constructing anetwork within communicable regions of respective wireless communicationapparatuses, without proving a specific base station or a controlstation, is suitable for constructing a small scale of personal areanetwork (PAN). In the Ad Hoc communication system, an access control isalso adopted to detect whether own transmission type of transmissiondoes not collide.

Further, in the wireless communication system, a method of inserting apreamble having a known pattern at the top of the packet forsynchronization among the communication apparatuses is generallyadopted.

For example, a system for wireless communication in which information issuperimposed on an extreme week impulse stream draws attention as awireless communication system realizing a near field ultra high speedtransmission and is expected to be actually used. The UWB transmissionsystem includes two types, namely, the DS-UWB system in which adiffusion speed of the information signal of the DS is increased to theupper limit and the impulse-UWB system in which the information signalis formed with an impulse scream having an extremely short period atabout hundreds picoseconds. Both systems provide high speed datatransmissions by diffusion toward an ultra high frequency band, forexample, from 3 GHz to 10 to execute transmission and reception. Theoccupied bandwidth is that of a GHz-order such that the value obtainedby dividing the occupied band width by its center frequency (forexample, 1 GHz to 10 GHz) becomes about 1. This has an ultra wide bandif it is compared with the band width generally used in the wireless LANor the like using the so-called W-CDMA or cdma2000 system, SS (SpreadSpectrum) or OFDM (Orthogonal Frequency Division Multiplexing) system.

Recently, in IEEE802.15.3, as an access control method for the ultrawide band communication, a data transmission method for a packetstructure including a preamble is proposed.

Further, after the transmission of data from an information transmissionsource communication apparatus, when an information reception targetcommunication apparatus side succeeds in data reception, as an automaticretransmission control method, a method of immediately returningreception confirmation information (immediate ACK) has been generallyadopted. In this case, at the information transmission sourcecommunication apparatus side recognizes the completion of the datatransmission when the immediate ACK can be received within apredetermined interval after the data transmission, but on the otherhand, when the immediate ACK cannot be received within the predeterminedinterval, it recognizes the incompletion of the data transmission. Inthe case of the latter, a data retransmission process is activated.

Further, in the wireless communication system, as another method toimprove a communication quality with avoiding collisions, the RTS/CTSmethod is given. In this case, before the transmission of the body ofthe information, the information transmission source communicationapparatus transmits an RTS (Request to Send: transmission request). Whenthe information reception target communication apparatus receives thisRTS, and if the data reception is possible, a CTS (Clear to Send:confirmation notice) is returned as the response. Then, afterestablishment of connection between the apparatuses by interchanging theRTS/CTS information, the data transmission is executed.

Here, in the ultra wide band communication mentioned earlier, thecommunication is executed with extremely weak impulse streams, and thus,it has no specified frequency-like carrier. Thus, there is a problemthat it is difficult that the access control method on the basis of theCSMA/CA using the reception electric field intensity information (RSSI)cannot be adopted as it is.

On the other hand, in the reception apparatus, a system can beconsidered which transmits an access control signal to inform theperipherals about its reception condition during the interval for whichthe signal directed to own station is received. In this case, thecommunication apparatus during non-communication state holds the usecondition of the transmission path with a lead of the reception of theaccess control signal.

However, if the use of transmission is notified during communicationstate, the communication apparatus on the reception side is required totransmit and receive the data at the same time. Further, it is requiredto transmit the access control signal by using a signal of a differentfrequency band, changing the diffusion code, or selecting timings withwhich impulses do not overlap. This makes the control complicated.

Further, in such a wireless communication system as to hold the user ofthe transmission path on the basis of a preamble signal, if aretransmission control is automatically executed on the basis ofpresence and absence of return of a reception confirmation information(immediate ACK) within a predetermined interval, other communicationapparatuses cannot be known about the start of retransmission as long asthe preamble signal once added to the NACK information is nottransmitted from the information reception target. Thus, loss of time isexpected.

In addition, in the wireless communication system interchanging theRTS/CTS information, it is necessary to undergo a connection procedurebetween the information transmission source and the signal receptiontarget before the data transmission. Thus, the adoption of a methodusing the preamble signal corresponding to a redundant time added beforea signal will cause a problem that it takes for a long period to conductthe connection procedure.

DISCLOSURE OF THE INVENTION

The object of the present invention is to provide a superior wirelesscommunication system, a wireless communication apparatus, a wirelesscommunication method, and a computer program capable of preferablyexecuting the access control and as well as the retransmission controlfor avoiding collisions of communication.

A further object of the present invention is provide a superior wirelesscommunication system, a wireless communication apparatus, a wirelesscommunication method, and a computer program, capable of preferablyexecuting a retransmission control in addition to a suitable accesscontrol for avoiding collisions of communication in the ultra wide bandcommunication system.

A further object of the present invention is to provide a superiorwireless communication system, a wireless communication apparatus, awireless communication method, and a computer program, capable ofproviding a suitable access control or a suitable retransmission controlfor holding the use condition of the transmission path for the datacommunication or retransmission between other communication terminals bya currently non-communicating communication apparatus.

The present invention is provided in consideration of theabove-described problems and its first aspect is a wirelesscommunication system, comprising a plurality of communicationapparatuses, for dividing transmission data by a predetermined unit andeffecting data transmission, characterized in that

-   -   a communication apparatus of an information transmission source        forms a data packet by inserting a preamble signal into each        transmission data to transmit it, and    -   a communication apparatus being not currently communicating        recognizes that the transmission path is used for a        predetermined interval from when the preamble signal is        detected. According to the wireless communication system        regarding the first aspect, each communication apparatus can        hold the use condition of the transmission path on the basis of        the detection of the preamble signal and also in the Ad Hoc        communication, it can preferably provide the access control with        avoiding collision of communication.

However, the “system” here means an object in which a plurality ofapparatuses (or functional modules for providing a specified functions)logically congregating, and thus it is not in question as to whether ornot each apparatus or each module exists in a single case.

In the wireless communication system regarding the first embodiment ofthe present invention, the communication apparatus of the informationtransmission source constructs a data packet at a predetermined timeinterval unit and as well as inserts a preamble signal to transmit it.On the other hand, after reception of a data packet the informationreception target communication apparatus, in response to correctlyreceiving the data, generates an ACK information or in response toincorrectly receiving the data, generates an NACK information, forms anACK or an NACK packet into which the preamble signal is inserted toreturn it. After that, the above-mentioned information transmissionsource communication apparatus retransmits the data packet of theabove-described predetermined time interval unit only in response to thereception of the NACK packet.

In the case of such an automatic retransmission control, thecommunication apparatus currently non-communicating state can recognizethat the transmission path is used for the data retransmission for theinterval from when the detection of the NACK packet to when thedetection of the next ACK packet on the basis of the reception of thepreamble signal.

Further, other communication apparatuses currently non-communicatingstate can recognize on the basis of the detection of the preamble signalthe termination of the use of the transmission path, because it issupposed that a payload has a predetermined length, when an ACK packetcannot be detected until a predetermined interval elapsed from when thereception of the NACK packet.

Further, the information reception target apparatus may add a beaconsignal describing information regarding the communication of whichtransmission is permitted with priority to the top of the preamblesignal to transmit it. The communication apparatus specified by thebeacon signal may transmit a data packet of a predetermined unit whenthe data to be transmitted to the information reception target apparatusexists.

In this case, other communication apparatuses currentlynon-communicating state can recognize that the transmission path is usedfor the interval corresponding to the packet length from when the beaconsignal is received on the basis of the detection of the preamble signal.

Further, the information transmission source apparatus may transmit atransmission request packet (RTS) into which a preamble signal isinserted when no preamble signal is detected for a predeterminedinterval. The information reception target communication apparatus mayreturn a confirmation notice packet (CTS) in response to the receptionof the transmission request packet (RTS) to start the data transmissionthrough the connection procedure on the basis of the RTS/CTS.

In this case, other communication apparatus currently non-communicatingcan detect an NACK packet from when the reception of the confirmationnotice (CTS) packet to when a predetermined interval elapsed on thebasis of the detection of the preamble signal and can recognize the useof the transmission path for the interval up to the detection of thenext ACK packet.

As this time, the information above-mentioned transmission sourcecommunication apparatus may include an element of the transmissionrequest (RTS) for the next data packet transmission in the data packetwhen there is subsequent transmission data. Furthermore, the informationreception target communication apparatus may include an element of theconfirmation notice (CTS) in the ACK packet or the NACK packetcorresponding to the received data packet.

In this case, because the connection procedure between transmissionapparatus and the reception apparatus on the basis of the RTS/CTS can beincluded in the net data transmission or the corresponding ACK returnthough the data packet transmission continues, the redundancy in theconnection procedure can be eliminated, and the communication intervalnecessary for the same data transmission amount can be shortened.

Further, a second aspect of the present invention is a computer programdescribed in a computer-readable format to execute on a computer systema wireless communication process in a wireless network constructed witha plurality of communication apparatus, characterized by comprising:

-   -   a buffering step dividing transmission data by a predetermined        unit;    -   a transmission data processing step adding a predetermined        preamble signal to the divided data to form a transmission        packet;    -   a preamble detection step detecting a preamble signal on a        transmission path;    -   a transmission step transmitting the formed packet when the        preamble signal is not detected at said preamble detection means        for a predetermined interval;    -   a reception step receiving the signal added to the preamble        signal in response to the detection of the preamble signal; and    -   a reception data processing step analyzing the information        received by said reception step.

The computer program regarding the second aspect of the presentinvention defines a computer program described in a computer-readableformat to execute a predetermined process on a computer system. In otherwords, installing the computer program regarding the second aspect ofthe present invention into a computer system exercises a cooperativefunction on the computer system to provide the same operational effectas the wireless communication system regarding the first aspect of thepresent invention.

Further objects, features, and advantage effects of the presentinvention will become more readily apparent from the following detaileddescription taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a drawing illustrating an arrangement example of communicationapparatuses constructing a wireless communication system regarding anembodiment of the present invention;

FIG. 2 is a drawing illustrating a structural example of a transmissionframe period used in the wireless communication system regarding anembodiment of the present invention;

FIG. 3 is a drawing illustrating an operation example of a communicationsequence when a prioritized transmission source is specified;

FIG. 4 is a drawing illustrating a communication sequence when aprioritized transmission source is not specified;

FIG. 5 is a drawing illustrating a communication sequence example inwhich data is continuously transmitted in the data transmission using aconnection procedure on the basis of the RTS/CTS;

FIG. 6 is a drawing illustrating an operation sequence example of dataretransmission;

FIG. 7 is a drawing schematically illustrating a functional structureexample of wireless communication apparatus capable of preferablyoperating in a wireless communication system regarding an embodiment ofthe present invention;

FIG. 8 is a drawing illustrating a structure of the beacon signal usedin the wireless system regarding an embodiment of the present invention;

FIG. 9 is a drawing illustrating a structure of a data packet signalused in the wireless system regarding an embodiment of the presentinvention;

FIG. 10 is a drawing illustrating a structure of an ACK packet signalused in the wireless system regarding an embodiment of the presentinvention;

FIG. 11 is a drawing illustrating a structure of an NACK packet signalused in the wireless system regarding an embodiment of the presentinvention;

FIG. 12 is a drawing illustrating a structure of a transmission request(RTS) packet signal used in the wireless system regarding an embodimentof the present invention;

FIG. 13 is a drawing illustrating a structure of a confirmation notice(CTS) packet signal used in the wireless system regarding an embodimentof the present invention;

FIG. 14 is a flow chart illustrating an operation procedure executedwithin the wireless system by the wireless communication system shown inFIG. 7; and

FIG. 15 is a flow chart illustrating a detailed procedure of the accesscontrol corresponding to step S3 in FIG. 14.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinbelow will be described an embodiment of the present inventionwith reference to drawings.

FIG. 1 shows an arrangement example of communication apparatusesconstructing a wireless communication system of an embodiment of thepresent invention. The same drawing illustrates the condition in which acommunication apparatus #1 to a communication apparatus #7 aredistributed on the same space.

The broken lines in the same drawing show communication areas ofrespective communication apparatuses in which each of the communicationapparatus is mutually communicable with other communication apparatusesexisting within the area and also provides interference at the area.

That is, in the example shown in FIG. 1, the communication apparatus #1exists at an area communicable with the adjacent communicationapparatuses #2, #3, and #7. The communication apparatus #2 exists at anarea communicable with the adjacent communication apparatuses #1 and #3.The communication apparatus #3 exists at an area communicable with theadjacent communication apparatuses #1, #2, and #5. The communicationapparatus #4 exists at an area communicable with the adjacentcommunication apparatus #5. The communication apparatus #5 exists at anarea communicable with the adjacent communication apparatuses #3, #4,and #6. The communication apparatus #6 exists at an area communicablewith the adjacent communication apparatus #5. The communicationapparatus #7 exists at an area communicable with the adjacentcommunication apparatus #1.

As described later, according to the present invention, eachcommunication apparatus establishes the access control by using onewireless transmission path in a time-divisional manner in considerationof mutual influence with other communication apparatuses existing aroundthe communication apparatus.

FIG. 2 shows an example of a frame structure used in the wirelesscommunication system of the embodiment.

The frame structure shown in the drawing is defined by the transmissionof a beacon signal (B) from each wireless communication apparatus,wherein a transmission frame period and a different offset timing areset for each wireless communication apparatus. That is, each wirelesscommunication apparatus is set to have a different beacon transmissionposition to transmit a beacon with mutually avoiding collisions to forman autonomous distributed type of Ad Hoc wireless network. The beaconsignal may have description of various types of information to controlthe communication operation at the communicable area of the wirelesscommunication apparatus.

FIG. 3 shows an operation example of the communication sequence when aprioritized transmission source is specified. The example shown in thesame drawing illustrates the sequence capable of communication witheliminating the complicated connection procedure by that a communicationapparatus as an information reception target specifies the communicationapparatus effecting a prioritized transmission just after own beaconsignal.

In the drawing, the communication apparatuses #1, #2, #3, and #4 arearranged, and the communication apparatus #1 is communicable with theadjacent communication apparatus #2. The communication apparatus #2 iscommunicable with the adjacent communication apparatuses #1 and #3. Thecommunication apparatus #3 is communicable with the adjacentcommunication apparatuses #2 and #4. The communication apparatus #4 iscommunicable with the adjacent communication apparatus #3. Further, thecommunication apparatus #4 is not audible to the communication apparatus#2, and the communication apparatus #1 is not audible to thecommunication apparatus #3. Thus, they are hidden terminals for eachother.

When the beacon signal is transmitted from the communication apparatus#3, the adjacent communication apparatuses #2 and #4 receive it. Then,the communication apparatus #2 specified as the prioritized transmissiontarget can transmit the data.

As this time, the communication apparatus #4, a hidden terminal viewedfrom the communication apparatus #2, detects the use of the transmissionpath using the beacon signal to execute a control without transmissionuntil the termination of this communication. More specifically, thecommunication apparatus #4 detects that another communication apparatus#2 is specified as the prioritized transmission source on the basis ofthe beacon signal from the communication apparatus #3 to recognize thatthe transmission path is used up to the detection of the ACK packet forthe transmission data from the communication apparatus #2.

Further, the communication apparatus #1 is a hidden terminal viewed fromthe communication apparatus #3 and thus, cannot receive the beaconsignal, but can similarly detect the use of the transmission path on thebasis of the preamble signal added to the top of the data packetaccording to the data transmission by the communication apparatus #2 toexecute a control of non-transmission until the termination of thiscommunication.

As shown in FIG. 3, a preamble signal is always added to top of thebeacon signal, the data packet, and the ACK packet. In the drawing, theparts designated with “P” correspond the preamble. Addition at the startof transmission of each signal enables the communication apparatuses todetect the use of the transmission path by adjacent communicationapparatuses.

The preamble signal is generally formed with the known stringinformation and transmitted, so that it can be more easily received thanthe net transmission data. Thus, the communication apparatuses at thecommunicable area can surely detect this. This is also applicable to theUltra Wide Band communication having no carrier of a specific frequency.

In the operation sequence example shown in FIG. 3, the judgment of thetermination of the communication is triggered by the release of thetransmission path caused by the return of the ACK from the communicationapparatus #3, and in addition, it can be done by approximatelycalculating the termination time of the communication from theinformation described at the header part of the data. Alternatively, itmay be judged by no detection of the preamble over a predeterminedinterval.

FIG. 4 illustrates an operation example of the communication sequencewhen no priority transmission source is specified. In the example shownin the same drawing, the communication apparatus as the informationreception target transmits a transmission request (RTS), and thecommunication apparatus as the reception target returns the confirmationnotice (CTS) with informing the communication apparatus at the positionshowing a possibility of a hidden terminal about the use of the wirelesstransmission path to execute the data communication.

In the drawing, it is assumed that the communication apparatuses #1, #2,#3, and #4 are in the same position relation as that in FIG. 3. Thecommunication apparatus #2 intending to transmit data transmits atransmission request (RTS) to the communication apparatus #3, and thecommunication apparatus #3 returns the confirmation notice (CTS) to thecommunication apparatus #2.

At this point, the communication apparatuses #1 and #4 at the positionsshowing a possibility of making them hidden terminals viewed from boththe communication apparatuses #2 and #3 execute controls withouttransmission, respectively, up to the termination of the communicationby detection of the use of the transmission path.

More specifically, the communication apparatus #1 detects the start ofthe data transmission of which transmission source is anothercommunication apparatus #2 on the basis of the RTS packet to obtain thetimings of the data transmission of the net data and the return of thecorresponding ACK packet to recognize that the transmission path is usedfor the interval. Further, the communication apparatus #4 detects thestart of data transmission of which reception target is anothercommunication apparatus #3 on the basis of the CTS packet to recognizethat the transmission path is used up to the detection of the return ofthe ACK packet from the communication apparatus #3.

As shown in FIG. 4, a preamble signal is always added to the RTS packet,the CTS packet, a data packet, and an ACK packet. In the drawing, theparts designated with “P” correspond the preamble. Sure addition at thestart of transmission of each signal enables the adjacent communicationapparatuses to detect the use of the transmission path. The preamblesignal is generally formed with the known string information andtransmitted, so that it can be more easily received than the nettransmission data. Thus, the respective communication apparatuses at thecommunicable area can surly detect this. This is also applicable to theUltra Wide Band communication having no carrier of a specific frequency.

In the operation sequence example shown in FIG. 4, the judgment of thetermination of the communication is triggered by the release of thetransmission path caused by the return of the ACK from the communicationapparatus #3, and in addition, it can be done by approximatelycalculating the termination time of the communication from theinformation described at the header part of the data. Alternatively, itmay be judged by no detection of the preamble over a predeterminedinterval.

FIG. 5 illustrates a communication sequence example continuouslytransmitting data in the data transmission using the connectionprocedure on the basis of RTS/CTS. In the example of the same drawing,if a plurality of data packets are successively transmitted, the ACKinformation is once received from the reception target to inform theperiphery about the successive use of the transmission path to continuethe data transmission.

In the drawing, it is assumed that the communication apparatuses #1, #2,#3, and #4 are in the same position relation as that shown in FIG. 3. Ifthe communication apparatus #2 executes the data transmission to thecommunication to the communication apparatus #3 in accordance with apredetermined access control, and if the data further continue, anelement of the RTS is also added into the payload (data body) or theheader information for the next data transmission.

On the other hand, the communication apparatus #3 side returns an ACK(or NACK) packet to the communication apparatus #2 after the completionof the data packet. Then, the element of the CTS included in the ACKinformation is returned, which enables the communication apparatus #2 tosuccessively transmit the data.

At this point, the communication apparatus #4 as a hidden terminalviewed from the communication apparatus #2 receives the ACK includingthe element of the CTS to hold the continuation of the communicationdirected to the communication apparatus #3 to detect the use of thetransmission path to execute a control without transmission until thetermination of the communication.

Further, because the communication apparatus #2 continues to transmitthe data transmission, the communication apparatus #1 as a hiddenterminal viewed from the communication terminal #3 receives the datapacket including the element of the RTS to similarly detect the use ofthe transmission path to execute a control without transmission untilthe termination of the communication.

When the communication apparatus #2 does not transmit data including theelement of the RTS or when the communication apparatus #3 returns a pureACK including no element of the CTS, the continuous communicationterminates finally. The judgment of the termination of the communicationis, as shown in the drawing, triggered by the release of thetransmission path caused by the return of the ACK from the communicationapparatus #3, and in addition, it can be made by approximatelycalculating the termination time of the communication from theinformation described at the header part of the data packet.Alternatively, it may be judged by no detection of the preamble over apredetermined interval.

As shown in FIG. 5, the preamble signal is always added to the top ofthe data packet or the ACK (or NACK) packet. In the drawing, the partsof designated with “P” correspond the preamble and the addition at thestart of transmission of each signal enables the communicationapparatuses to detect the use of the transmission path by adjacentcommunication apparatuses. The preamble signal is generally made up ofthe known string information to be transmitted, so that it can be moreeasily received than the net transmission data. Thus, the communicationapparatuses at the communicable area can surely detect this. This isalso applicable to the Ultra Wide Band communication having no carrierof a specific frequency.

Further, as shown in FIG. 5, because the connection procedure betweenthe transmission apparatus and the reception apparatus on the basis ofthe RTS/CTS can be included in the net data transmission or thecorresponding ACK return if the data packet transmission continues, theredundancy in the connection procedure can be eliminated and thecommunication interval necessary for the same data transmission amountcan be shorted.

FIG. 6 shows an operation sequence example for the data retransmission.In the example shown in the same drawing, when the communicationapparatus as a transmission source receives the NACK packet from thereception target, the periphery is informed of execution of thecontinued retransmission to continue the data retransmission.

In the drawing, when the communication apparatus #2 is transmitting adata packet to the communication apparatus #3 in accordance with thepredetermined access control, and when the data includes an error at thecommunication apparatus #3, the NACK in formation is generated. Aftertermination of the data, the NACK packet is returned to thecommunication apparatus #2 from the communication apparatus #3. Here, apreamble signal is added to the top of the NACK packet. Thecommunication apparatus #2 receiving the NACK information can continuethe data retransmission.

During this, the communication apparatus #4, a hidden terminal withrespect to the communication apparatus #2, holds the continuation of theretransmission to the communication apparatus #3 by receiving the NACKpacket to detect the use of the transmission path and executes a controlwithout transmission until the termination of the communication. Morespecifically, on the basis of the NACK packet, the start of the dataretransmission of which reception target is another communicationapparatus #3 is detected, and thus it is possible to recognize that thetransmission path has been used until the return of the ACK packet fromthe comniunication apparatus #3 is detected.

Further, the retransmission of the data from the communication apparatus#2 causes the communication apparatus #1, which is a hidden terminalfrom the communication apparatus #3, to similarly detect the use of thetransmission path on the basis of the preamble signal added to the topof the data packet to execute a control without transmission until thetermination of the communication.

Then, the return of an AeCK packet from the communication apparatus #2finally terminates the sequence communication. The judgment of thetermination of the communication is triggered by that the transmissionpath is released by the return of the ACK packet from the communicationapparatus #3 as shown in drawing and as well as may be made byapproximately calculating the termination time of the communication fromthe information described at the header part of the data packet.Alternatively, the transmission termination can be judged by that thepreamble signal is not detected for a predetermined interval.

As shown in FIG. 6, a preamble signal is always added to the top of thedata packet, the ACK packet, and the NACK packet. In the drawing, theparts of designated with “P” correspond the preamble. Addition at thestart of transmission of each signal enables the communicationapparatuses to detect the use of the transmission path by an adjacentcommunication apparatus. The preamble signal is generally made up of theknown string information to be transmitted, so that it can be moreeasily received than the net transmission data. Thus, the communicationapparatuses at the communicable area can surely detect this. This isalso applicable to the Ultra Wide Band communication having no carrierof a specific frequency.

FIG. 7 schematically illustrates a functional structure example of awireless communication apparatus capable of preferably operating in awireless system regarding an embodiment of the present invention. Thewireless communication apparatus shown in the drawing comprises aninterface 101, a transmission buffer 102, a wireless transmissionsection 103, a preamble insertion section 104, an antenna 105, apreamble detection section 106, a wireless reception section 107, acentral control section 108, a reception buffer 109, a receptionconfirmation information generation section 110, a transmission dataprocessing section 111, a reception data processing section 112, and aninformation storing section 113.

The interface 101 interchanges various types of information withinformation processing units such as units connectable to the wirelesscommunication apparatus (for example, a personal computer (PC) or anupper position application operative on the units).

The transmission buffer 102 fragmentizes the data transmitted from theunit or an upper position application via the interface 101 by apredetermined unit and temporarily stores the fragmentized data.

The wireless transmission section 103 executes a modulation process toobtain, for example, an ultra wide band signal to wirelessly transmitthe data. The ultra wide band signal is formed with an impulse signalstream having an extremely short period about hundreds picoseconds. Inthis embodiment, no preamble signal is detected for a predeterminedinterval, the transmission operation of the data packet, a transmissionrequest (RTS), or the beacon signal is started.

The preamble insertion section 104 adds a predetermined preamble signalto an ultra wide band signal, namely, adds it just before transmissionof a packet. The preamble signal is generally formed with known stringinformation to transmit it.

The antenna 105 wirelessly transmits a signal to another wirelesscommunication apparatus and collects the signals from other wirelesscommunication apparatuses. The antenna 105 may be of atransmission/reception type.

The preamble detection section 106 detects the preamble formed with theknown stream added to the top of the ultra wide band signal collected bythe antenna 105 at the timing instructed by the central control section108.

The wireless reception section 107 receives the signals such as the dataor a beacon signal transmitted from other wireless communicationapparatuses. In this embodiment, the wireless receiving section 107receives the signal added to the preamble signal in response to thedetection of the preamble signal.

The central control section 108 integrally executes a sequence controlin the sequence data communication and the access control of thewireless transmission path in accordance with the execution procedureinstructions stored in the information storing section 113.

The reception buffer 109 stores the data received by the wirelessreception section 107 and judges whether or not an error exists in thedata.

The reception confirmation section 110 generates the ACK informationwhen the data is correctly received and generates the NACK informationwhen the data is incorrectly received. The central control section 108transmits the ACK information and the NACK information to thetransmission data processing section 111 to generate the ACK packet orthe NACK packet.

The transmission data processing section 111 takes out the fragmentizeddata stored in the transmission buffer 102 to generate a transmissionpacket, a transmission request (RTS), and a confirmation notice (CTS),and the periodical beacon signal at a predetermined frame period. In thebeacon signal, it is possible to describe specification of a prioritizedtransmission source.

The reception data processing section 112 analyses the data that can bereceived from other wireless communication apparatus. The reception datadescribed here includes the beacon signal transmitted at a predeterminedframe period from another communication apparatus, the data packet fromthe other wireless communication apparatus as a transmission source, theACK packet from another wireless communication apparatus as a receptiontarget, the confirmation notice (CTS) returned in response to thetransmission request (RTS) packet, and the like. When the beacon signalis received, the prioritized transmission source information isanalyzed.

The information storing section 113 stores the execution procedureinstructions for the sequence operation and temporarily storesinformation regarding the access control.

FIG. 8 illustrates the structure of the beacon signal used in thewireless system regarding an embodiment of the present invention. Thebeacon signal shown in the drawing comprises a header informationsection and a payload information section after a predeterminedpreamble.

The header information section comprises an identifier indicative of aBeacon (Beacon), a data length of the information, the information ofthe transmission source, the information of the reception group, and theerror detection information of the header (HCS: Head Check Sequence).

Further, to the payload information section, the specifying informationof a prioritized transmission apparatus or the like set at needs isadded, and error detection information (CRC: Cyclic Redundancy Code) ofthe payload is added at the most rear end.

FIG. 9 illustrates a structure of the data packet signal used in thewireless system regarding an embodiment of the present invention. Thedata packet in the drawing comprises a header information section and apayload information section after a predetermined preamble.

The header information section comprises an identifier indicative of theData (Data), a data length of the information, information of atransmission source address, information of a reception target address,and error detection information of the header (HCS).

Further the payload information section comprises the data payload inwhich fragmentation is carried out by an information amount of apredetermined time unit. If the transmission of the data packetscontinues, it is possible to include an element of the RTS for next datatransmission in the payload. Further, the element of the RTS can beincluded in the header information section (refer to FIG. 5).

FIG. 10 illustrates the structure of the ACK packet used in the wirelesssystem regarding an embodiment of the present invention. The ACK packetshown in the drawing is made up only of a header information sectionfollowing a predetermined preamble.

The header information section comprises an identifier indicative of anormal reception confirmation (ACK), a data length of the information,the information of the transmission source address, the information ofthe reception target address, and the error detection information of theheader (HCS). Further, if the data packet transmission continues, it ispossible to include an element of the CTS for the next data transmission(refer to FIG. 5).

FIG. 11 illustrates a structure of the NACK packet used in the wirelesssystem regarding an embodiment of the present invention. The NACK packetshown in the drawing is made up only of the header information sectionfollowing to a predetermined preamble.

The header information section comprises an identifier indicative of anerror reception confirmation (NACK), a data length of the information,information of the transmission source address, information of thereception target address, and error detection information of the header(HCS).

FIG. 12 shows a structure of a transmission request (RTS) packet signalused in the wireless system regarding an embodiment of the presentinvention. The RTS packet shown in the drawing is formed only with aheader information section following a predetermined preamble.

The header information section comprises an identifier indicative of thetransmission request (RTS), a data length of the information,information of a transmission source address, information of a receptiontarget address, and error detection information of the header (HCS).

FIG. 13 shows a structure of a confirmation notice (CTS) packet signalused in the wireless system regarding an embodiment of the presentinvention. The CTS packet shown in the drawing is formed only with aheader information section following a predetermined preamble.

The header information section comprises an identifier indicative of theconfirmation notice (CTS), a data length of the information, informationof a transmission source address, information of a reception targetaddress, and error detection information of the header (HCS).

FIG. 14 shows an operational procedure executed within the wirelesssystem by the wireless communication system shown in FIG. 7 in the formof a flow chart. This operation procedure is actually provided in thecondition that the central control section 108 executes the executionprocedure instructions stored in the information storing section 113.

In the interface 101 of the wireless communication apparatus, it isjudged whether a transmission request of the data is received from aunit externally connected with the interface 101 of the wirelesscommunication apparatus (or an upper layer application activated on theunit)(step S1).

When the data transmission request is detected, the data is fragmentizedby a predetermined unit to store the data in the transmission buffer 102(step S2).

After this, via a predetermined access control process (step S3), it isjudged whether the transmission data in the transmission buffer 102 canbe transmitted to the wireless transmission path.

Here, if communication by another communication apparatus is carried outwithin the communicable area of the wireless communication apparatus, apredetermined access control process (step S3) is continued. If no othercommunication apparatus carried out communication, it is in thecondition that the transmission to the wireless transmission path ispossible. The detailed description about the access control process willbe made later.

Next, the beacon signal from the information reception target isreceived to judge whether the reception region comes (step S5). Here,when the reception region does not come, the processing returns to stepS3 to try the predetermined access control process again.

If it is clear from the reception of the beacon signal that it is withinthe reception region of the information reception target, it is judgedwhether own station is specified as a prioritized transmission source(step S6). If own station is specified as a prioritized transmissionsource, the processing proceeds to step S9 to transmit the data (Data)packet to which a preamble signal is added.

On the other hand, if it is not specified as the prioritizedtransmission target, the preamble+transmission request (RTS) signal istransmitted to the reception target communication apparatus (step S7).After this, only when a for-own station confirmation notice (CTS) packet(step S8), the data packet to which a preamble is added is transmitted(step S9).

Here, if the for-own station confirmation notice (CTS) for the RTSpacket transmitted by own station is not received (step S8), theprocessing returns to step S5 to repeat the transmission process for theRTS after it is confirmed again as to whether it is within theinformation transmission region.

After the transmission of the data, when the for-own-station NACKinformation is received (step S10), the processing returns to step S9 toexecute retransmission of the data.

Further after the transmission of the data, when the for-own-station ACKinformation is received (step S11), it is judged whether transmissiondata exists continuously in step S12. If the transmission data existcontinuously, the processing proceeds to the step S9 to take out thefragmentized next data from the transmission buffer 102 to execute thedata transmission.

Here, if no continuous data exist, the sequence data transmissionprocessing is terminated and the processing returns to the first stepS1.

Further, if neither the ACK packet nor the NACK packet are receivedwithin a predetermined reception confirmation interval, the processingbranches off from “No” in step S11 and returns to step S5, where it isconfirmed again whether the information transmission region comes, andthen, the transmission process for the RTS is executed to effect dataretransmission (ditto).

When receiving no data transmission request in the judgment in step S1,this wireless communication apparatus judges whether the top timing of atransmission frame period comes (step S13). When the top timing of atransmission frame period comes, a beacon is transmitted (step S14).After this, it is judged whether it exists within own reception region(step S15).

Here, if it is not the top timing of a frame period, or it is outsideown reception region, the processing returns to step S1.

Further, if it is within own reception region, a predetermined preamblesignal reception processing is executed (step S16).

At this point, if a for-own-station transmission request (RTS) packet isreceived (step S17), the confirmation notice (CTS) packet to which apreamble is attacked just after its end is returned (step S18).

Further, if a for-own-station data (Data) packet is received (step S19),a data reception of a predetermined unit is executed (step S20). Here,it is possible to adopt the structure that the wireless communicationapparatus as a transmission source of the for-own-station data isspecified as a prioritized transmission source (step S21).

It is judged whether the data is correctly received using the CRC at theend (step S22). If the data cannot be received, the NACK packet to whicha preamble is attacked just after its end is returned (S23). After that,the processing returns to step S15 to continue the reception processagain.

On the other hand, if the data is correctly received (step S22), the ACKpacket to which a preamble is attacked just after its end is returned(step S24). Then, the received data is supplied to an externallyconnected device through the interface 102 (or the upper layerapplication) (step S25), and the sequence data reception processterminates. After that, the processing returns to the first step S1.

Further, if no reception of for-own station data (step S19), theprocessing returns to step S15 again to continue to execute thesesequence reception processes only when it exists within the own-stationregion.

FIG. 15 shows a detailed procedure of the access control processcorresponding to the step S3 in FIG. 14 in a flow chart format.

First, time corresponding to the time unit of predetermined fragmentizeddata is set to an access timer (step S31). Then, it is judged whetherthe preamble signal is detected (step S32). If it is detected, then, theheader part is decoded.

Next, it is judged whether the RTS header is received (step S33). If theRTS header is received, successively it is judged whether Data header isincluded (step S34).

If the Data header is included, the time corresponding to the datalength of the data is set to the access timer (step S41), and thecontrol is effected to execute no transmission operation with therecognition that the transmission path is used for the interval up totime out (step S41).

On the other hand, if no Data header is included, the time up to theData timing expected to be subsequently transmitted is set to the accesstimer (step S40).

Further, other than the RTS header, if the CTS header is received (S35),time corresponding to the data length of the data is set to the accesstimer (step S41), the control is effected to execute no transmissionoperation with the recognition that the transmission path is used byhidden terminals for the interval up to time out (step S41).

Further, other than the RTS header and the CTS header, if Data header isreceived (step S36), the time corresponding to the data length of thedata is set to the access timer (step S41).

Further, other than the RTS header, the CTS header and the Data header,if the NACK header is received (S37), time corresponding to the datalength of the data is set to the access timer (step S41), the control iseffected to execute no transmission operation with the recognition thatthe transmission path is used by hidden terminals for the interval up totime out.

If no, and if the ACK header is received (step S38), successively it isjudged whether the CTS header is included (step S39). If the CTS headeris included, time corresponding to the data length of the data is set tothe access timer (step S41), the control is effected to execute notransmission operation with the recognition that the transmission pathis used for continuous data transmission for the interval up to timeout. On the other hand, if no CTS header is included, the setting in theaccess timer as a target of the ACK is released (step S42), and thesequence access control process is terminated and the processing exitsthe subroutine.

Further, if no header is received after the detection of the preamblesignal, the time corresponding to the time unit of the predeterminedfragmentized data is set to the access timer (step S43).

After that, if no preamble signal is detected and if a timer value isnewly set, it is judged whether the access timer become “time out” (stepS44). Then, if in case of “time out”, the sequence access controlprocess is terminated and the processing exits the subroutine.

If the access timer does not become “time out”, the processing returnsto step S32, where the above-mentioned sequence process is repeateddepending on whether a new signal is received up to time when the settimer becomes “time out”.

In this embodiment, as described above, the preamble signal is alwaysattacked to the top of a packet. The regularly attachment at thetransmission start of each signal provides the detection of the use ofthe transmission path by the peripheral communication apparatuses. Thepreamble signal, generally transmitted with the structure includingknown string data, can be easily received, so that each communicationapparatus within the communicable region can surly detect it.

Appendix

As described above, the present invention is described in detail withreference to the specific embodiment. However it is obvious that theperson in the art can make modification or replacement within the regionwithout departing from the subject of the present invention. That is,the present invention has been disclosed in an exemplary mode and shouldnot be interpreted restrictively. To judge the subject matter of thepresent invention, Claims should be referred.

Industrial Applicability

According to the present invention, a superior wireless communicationmethod, a superior wireless communication apparatus, a superior wirelesscommunication method, and a superior computer program, capable of apreferable access control with avoiding collision of communication and aretransmission control in the ultra-wide band communication system areprovided.

Further, according to the present invention, there are provided asuperior wireless communication method, a superior wirelesscommunication apparatus, a superior wireless communication method, and asuperior computer program, capable of a preferable access control or apreferable retransmission control with holding the use condition of thetransmission path for the data communication or retransmission betweenother communication terminals by currently non-communicatingcommunication apparatuses.

According to the present invention, it is surly specified that when thedata is correctly received, the ACK information is returned, and if thedata is not correctly received, the NACK information is returned. Thisprovides the communication method capable of informing peripheralcommunication apparatuses about the repeatedly use of the transmissionpath.

Further, according to the present invention, transmitting a beaconsignal describing the information of the wireless communicationapparatus of which transmission is prioritized preferably avoidscollisions among communication apparatuses without using previouslyinterchanging the transmission request (RTS) and the confirmationnotices (CTS) before the data communication.

Further, according to the present invention, if a plurality offragmentized data pieces are transmitted, transmitting data packet ofthe next unit after the reception of the ACK packet for the data packetpreferably prevents occurrences of collisions during continuously usethe transmission path.

Further, according to the present invention, if no prioritizedtransmission is permitted, or if the ACK cannot be received, the use ofthe procedure of exchanging the transmission request (RTS) and theconfirmation notice (CTS) preferably avoids collisions among thecommunication apparatuses.

1. A wireless communication system having a plurality of communicationapparatuses for dividing transmission data by a predetermined unit andeffecting data transmission, in that the system comprising: aninformation transmission source communication apparatus for forming adata packet by inserting a preamble signal into each transmission dataand and transmitting the formed data packet; and a communicationapparatus not currently communicating for recognizing that thetransmission path is used for a predetermined interval from a time whenthe preamble signal is detected.
 2. The wireless communication system asclaimed in claim 1, wherein the information transmission sourcecommunication apparatus forms the data packet at a predetermined timeunit, and further comprising: an information reception targetcommunication apparatus for generating acknowledge (ACK) information inresponse to the success in correctly receiving the data and forgenerating not acknowledge (NACK) information in response to a failurein correctly receiving the data, forms an ACK or NACK packet to which apreamble signal is inserted, and returns it, just after the reception ofthe data packet; said information transmission source communicationapparatus retransmits the data packet of said predetermined time unit inresponse to the reception of the NACK packet; and said communicationapparatus not currently communicating recognizes a use of thetransmission path for retransmission based on the reception of thepreamble signal for a period from the detection of the NACK packet todetection of the next ACK packet.
 3. The wireless communication systemas claimed in claim 2, wherein other communication apparatuses notcurrently communicating recognize the termination of the use of thetransmission path when the ACK packet cannot be detected based on thedetection of the preamble signal until a predetermined elapsed time fromwhen the NACK packet is received.
 4. The wireless communication systemas claimed in claim 2, wherein the information reception targetcommunication apparatus adds the preamble signal to a top of a beaconsignal describing information regarding a communication apparatus ofwhich transmission is permitted with priority, and transmits the beaconsignal; the communication apparatus specified by the beacon signaltransmits a predetermined unit of data packet when there is data to betransmitted to said information reception target apparatus; and othercommunication apparatuses being not currently communicating recognizebased on the detection of the preamble signal the use of thetransmission path for the time interval corresponding to the packetlength from when said beacon signal is received.
 5. The wirelesscommunication system as claimed in claim 2, wherein said informationtransmission source communication apparatus transmits a transmissionrequest packet (RTS) into which the preamble signal is inserted when nopreamble signal is detected for a predetermined time interval; and saidinformation reception target communication apparatus returns aconfirmation notice packet (CTS) in response to the reception of atransmission request packet (RTS).
 6. The wireless communication systemas claimed in claim 5, wherein said other communication apparatus notcurrently communicating recognizes based on the detection of thepreamble signal the use of the transmission path from when the NACKpacket is detected, during a predetermined interval from the receptionof the confirmation notice (CTS) packet, to when the next ACK packet isdetected.
 7. The wireless communication system as claimed in claim 5,wherein said information source communication apparatus makes the datapacket include therein an element of the transmission request (RTS) fora next data packet transmission when following transmission data exists.8. The wireless communication system as claimed in claim 5, wherein saidinformation reception target communication apparatus makes the ACKpacket or the NACK packet corresponding to the received data packetinclude an element of confirmation notice (CTS).
 9. A wirelesscommunication apparatus operating within a wireless network constructedof a plurality of communication apparatuses comprises: buffer means fordividing transmission data by a predetermined unit; transmission dataprocessing means for adding a predetermined preamble signal to dividedtransmission data from the buffer means to form a transmission packet;preamble detection means for detecting a preamble signal on atransmission path; and transmission means for transmitting the formedpacket when no preamble signal is detected for a predetermined intervalat said preamble detection means.
 10. The wireless communicationapparatus as claimed in claim 9, further comprising: reception means forreceiving a signal added to the preamble signal in response to thedetection of the preamble signal; and reception data processing meansfor analyzing the signal received by said reception means.
 11. Thewireless communication apparatus as claimed in claim 10, said receptiondata processing means generates acknowledge (ACK) information inresponse to correctly receiving a for-own-station data and notacknowledge (NACK) information in response to incorrectly receiving thefor-own-station data; said transmission data processing means forms anACK packet or an NACK packet into which a preamble signal is inserted;and said transmission means transmits the ACK packet or the NACK packetjust after the reception of the data.
 12. The wireless communicationapparatus as claimed in claim 11, wherein upon not currentlycommunicating, said reception data processing means recognizes use ofthe transmission path for the data retransmission from when the NACKpacket is detected to when the next ACK packet is detected.
 13. Thewireless communication apparatus as claimed in claim 11, said receptiondata processing means recognizes a termination of use of thetransmission path when no ACK packet is detected until a predeterminedinterval has elapsed from when the NACK packet is received.
 14. Thewireless communication apparatus as claimed in claim 10, saidtransmission data processing means generates a beacon signal describinginformation regarding a communication apparatus from which transmissionis permitted with priority; and said reception data processing meansanalyzes whether the transmission of its own station is permitted withpriority by analyzing the beacon signal.
 15. The wireless communicationapparatus as claimed in claim 14, wherein upon not currentlycommunicating, said reception data processing means recognizes use of atransmission path for a time interval corresponding to the packet lengthfrom when the beacon signal is received.
 16. The wireless communicationapparatus as claimed in claim 10, wherein said transmission dataprocessing means generates a transmission request (RTS) packet for adata transmission target; and in response to reception of thetransmission request (RTS) packet from another communication apparatusby said reception processing means, said transmission data processingmeans generates a confirmation notice (CTS) packet.
 17. The wirelesscommunication apparatus as claimed in claim 16, wherein upon notcurrently communicating, said reception data processing means recognizesuse of a transmission path from when a not acknowledge (NACK) packet isdetected, during a predetermined interval from the reception of theconfirmation notice (CTS) packet, to when a next acknowledge (ACK)packet is detected.
 18. The wireless communication apparatus as claimedin claim 16, wherein said transmission data processing means makes thedata packet include therein an element of the transmission request (RTS)for a next data packet transmission when a following transmission dataexists.
 19. The wireless communication apparatus as claimed in claim 16,characterized in that: said transmission data processing means makes anacknowledge (ACK) packet or a not acknowledge (NACK) packetcorresponding to the received data packet include an element of theconfirmation notice [CTS] therein.
 20. A wireless communication methodfor use in a wireless network constructed of a plurality of acommunication apparatuses comprising: a buffering step for dividingtransmission data by a predetermined unit; a transmission dataprocessing step for forming a transmission packet by adding apredetermined preamble signal to divided data from the buffering step; apreamble detection step for detecting a preamble signal on atransmission path; and a transmission step for transmitting the formedtransmission packet when no preamble is detected for a predeterminedinterval in said preamble detection step.
 21. The wireless communicationmethod as claimed in claim 20, further comprising: a reception step forreceiving a signal added to the preamble signal in response to thedetection of the preamble signal, and a reception data processing stepfor analyzing information received by said reception step.
 22. Thewireless communication method as claimed in claim 21, wherein in saidreception data processing step, in response to success in correctlyreceiving data directed to own station, acknowledge (ACK) information isgenerated, or in response to a failure in correctly receiving datadirected to own station, not acknowledge (NACK), information isgenerated; in said transmission data processing step, an ACK packet oran NACK packet into which the preamble signal is inserted is formed, andin said transmission step, the ACK packet or the NACK packet istransmitted just after the data reception.
 23. The wirelesscommunication method as claimed in claim 22, wherein upon not currentlycommunicating in said reception data processing step, it is recognizedthat the transmission path is used for data retransmission from when theNACK packet is detected to when a next ACK packet is detected.
 24. Thewireless communication method as claimed in claim 22, wherein in saidreception data processing step, it is recognized that use of thetransmission path is terminated when the ACK packet cannot be detecteduntil a predetermined time has elapsed from when the NACK packet isreceived.
 25. The wireless communication method as claimed in claim 21,wherein in said transmission data processing step, beacon signaldescribing information regarding the communication apparatus from whichtransmission is permitted with priority is generated; and in saidreception data processing step, it is analyzed whether own transmissionis permitted with priority by analyzing the beacon signal.
 26. Thewireless communication method as claimed in claim 25, wherein uponcurrently non-communicating, in said reception data processing step, itis recognized that a transmission path is used for the time intervalcorresponding to the packet length from when the beacon signal isreceived.
 27. The wireless communication method as claimed in claim 21,wherein in said transmission data processing step, a transmissionrequest (RTS) packet for the data transmission target is generated; orin said reception step, in response to the reception of a transmissionrequest (RTS) packet from another communication apparatus, in saidtransmission data processing step, a confirmation notice (CTS) packet isgenerated.
 28. The wireless communication method as claimed as claim 27,wherein upon currently non-communicating, in said reception dataprocessing step, it is recognized that the transmission path is usedfrom when a not acknowledge (NACK) packet is detected during apredetermined interval from the reception of the confirmation notice(CTS) packet to when a next acknowledge (ACK) packet is detected. 29.The wireless communication method as claimed in claim 27, wherein insaid transmission data processing step, the data packet is made toinclude therein an element of the transmission request (RTS) for a nextdata packet transmission when a following transmission data exists. 30.The wireless communication method as claimed in claim 27, characterizedin that: in said transmission data processing step, and acknowledge(ACK) packet or an not acknowledge (NACK) packet corresponding to thereceived data packet is made to include therein an element of theconfirmation notice (CTS).
 31. A computer program described in acomputer-readable format to execute on a computer system a wirelesscommunication process in a wireless network constructed of a pluralityof communication apparatuses, the program comprising: a buffering step,for dividing transmission data by a predetermined unit; a transmissiondata processing step, for adding a predetermined preamble signal todivided data from the buffering step to form a transmission packet; apreamble detection step, for detecting a preamble signal on atransmission path; a transmission step for transmitting the formedtransmission packet when no preamble signal is detected at said preambledetection means for a predetermined interval; a reception step forreceiving the signal added to the preamble signal in response to thedetection of the preamble signal; and a reception data processing stepfor analyzing the information received in said reception step.